Air Actions, Arizona

Particulate Matter Actions in Rillito, AZ

July 2006: Particulate Matter in Rillito, Arizona

EPA has signed a direct final rule determination, based on ambient monitoring data, that the Rillito area in Arizona has attained the short-term (24-hour) and long-term (annual) primary National Ambient Air Quality Standards (NAAQS) for particulate matter (PM-10). The Rillito area has not had an exceedance of either the annual or the 24-hour health-based standard since 1991. The Act and our regulations require three years of clean data to make this finding. Once this clean data finding is effective, the State will be relieved of certain attainment, reasonable further progress, and related requirements so long as the ambient air quality standard continues to be met. Our action will streamline the process for the Arizona Department of Environmental Quality (ADEQ) to request redesignation of this area to attainment.